Article:		What Is XQuery
Subject:		idref
Date:		2003-11-11 17:59:21
From:		Jyothi ratna
Hello, I am a beginner in Xquery.In my schema I have element which has IDREF attribute.I want to extract id value to which points and check whether that value is equivalent to some value. eg:<AUTHOR EMAILID ="psmith@sfsu.edu"> > <FNAME>smith</FNAME> <MI>j</MI> <LNAME>jen</LNAME> </AUTHOR> <PAPER PAPERID = 10 EMAILID = "sai@yahoo.com" > <MAINATHR>SHARMA</MAINATHR> <TITLE>ABC</TITLE> </PAPER> <PAPER PAPERID = 10 EMAILID = "sha@yahoo.com" > <MAINATHR>SHARMA</MAINATHR> <TITLE>ABC</TITLE> </PAPER> Here EMAILID is a IDREF attribute in PAPER element.I want to check the value of EMAILID of paper element and check if it is "sai@yahoo.com ".If it is "sai@yahoo.com" I have to retrieve paperid,author fname from the document.I think I may have to use dereference operator => but I do not know how to apply that in my situation.Could anybody please help me to solve this problem? Thanks, Sharma

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• idref
  2003-11-12 11:32:24 Per Bothner
  
  This should get you on the right track. Note that for more complex conditions you might want to use a 'where' clause rather than a [predicate].

  
  let $id := "sai@yahoo.com",
  for $paper in $doc/PAPER[@EMAILID = $id],
  for $author in $doc/AUTHOR[@EMAILID = $id]
  return
  <result PAPERID="{$paper/@PAPERID}">
  {$author/FNAME}
  <result>

  
  This assumes you have a specific emailid. If you want this for all emailids, you could do:

  
  for $paper in $doc/PAPER,
  for $author in $doc/AUTHOR
  where $paper/@EMAILID = $auther/$EMAILID
  return
  <result PAPERID="{$paper/@PAPERID}">
  {$author/FNAME}
  <result>

  
  XQuery does not have the => operator.